How would I pass a hex-value through a function?
I mean, what type would I use?

Currently I have two different functions. One
is used to change the screen resolution to 13h,
and the other is to change it back to 03h. I would
like to only have one function and pass the
screen-mode through that.

Any signed integer type will probably do for this specific example, but you might get the odd compiler warning if you try and pass a hex value with the most significant bit set (the function will think its a negative value)

11-09-2001

ender

Vid modes never even come close to FFh, so a short int would actually work fine. An integer is just a particular range of numbers. The base those numbers are in is irrelevant as long as the number is w/ in the range.